1. Field of the invention
This invention relates to a composition and process for inflating a safety crash bag.
2. Description of the prior art
In the prior art, the generation of nitrogen gas in order to fill an airbag for use as an aircraft or automobile safety crash bag has involved the use of azide compounds. Azide compounds such as sodium azide are highly toxic materials prior to combustion. Such azide salts also readily react with heavy metals such as copper, lead, etc. to form extremely sensitive solids that are subject to unexpected ignition or detonation and therefore require special handling in the manufacture, storage and disposal of such compounds.
Methods of generating nitrogen gas to fill a safety crash bag using metal salts of 5,5'-bitetrazole with oxidizers which contain no oxygen in the molecule are disclosed in Lundstrom et al U.S. Pat. No. 4,370,181. The prior art use of tetrazole compounds with oxygen containing oxidizers are dismissed in view of the fact that such compositions do not meet the present requirements for the generation of gases which are able to meet the industrial standards for toxicity with respect to such gases as carbon monoxide, carbon dioxide, etc. The disclosure of prior art non-azide nitrogen gas generants by Lundstrom et al are to various hydroxamine acid and hydroxylamine derivatives, various polymeric binders, hydrocarbons and carbohydrates which are oxidized to produce non-corrosive and, often termed, "non-toxic" gases. In addition, Lundstrom et al disclose as other approaches to non-azide nitrogen gas generants utilizing tetrazole compounds such as aminotetrazole, metal salts of aminotetrazole, or other tetrazole salts which contain hydrogen in the molecule. These are used in combination with oxygen containing oxidizers such as potassium perchlorate. Upon combustion, these compositions tend to form various toxic species such as hydrogen cyanide, nitrogen oxides, and carbon monoxide in unacceptable proportions so as not to meet the present toxicity requirements for the non toxicity of the gas generated.
In Shaw U.S. Pat. No. 4,369,079, solid, non-azide nitrogen gas generant compositions for inflation of a safety crash bag are disclosed as consisting essentially of a metal salt of a non-hydrogen containing a tetrazole compound in admixture with an oxidizer containing nitrogen. The specific tetrazole which is disclosed as useful is azobitetrazole.
In U.S. Pat. No. 3,910,595, an apparatus is described for aspirating air into a gas mixture used to inflate a crash restraint device.